1. Field of the Invention
The present invention relates to anti-submarine warfare (ASW) technologies and more particularly to a non-acoustic technique for remotely sensing the presence of submerged submarines from another submarine.
2. Description of the Prior Art
The detection and localization of submerged submarines has traditionally been dependent on passive acoustic techniques and/or magnetic anomaly detection. A major disadvantage of acoustic techniques is the loss of detection capability with advances in the development of noiseless or "silent" submarines. Another disadvantage is the cost and time required to install and maintain large numbers of submerged acoustic sensing devices over wide areas of the ocean in order to achieve the objective.
A submarine detection technique that avoids this disadvantage uses the internal waves created by a moving submarine as the sensed parameter. Internal waves are subsurface waves found between layers of water of different density or within ocean layers where vertical density gradients exist. [see "The Encyclopedia of Oceanography," Vol. I, Rhodes Fairbridge Edition, pages 402-408 (Reinhold Publishing Corp., New York, 1966)]. One way to measure such internal waves is to construct a profile of ocean water temperatures as a function of depth. A technique employed in the past for measuring such profiles involves the use of many temperature sensing elements (thermistors) spaced on a cable and towed by a ship. This is costly, time consuming and generally unsuited to high spatial and temporal resolution coverage of large ocean areas.
This invention is directed to submarine detection by the measurement of sub-surface ocean temperatures while avoiding the foregoing disadvantages.
A general object of the invention is the provision of a method of sub-surface submarine detection by remotely and rapidly measuring ocean temperature profiles from a second search submarine.
Another object is the provision of a method of sub-surface submarine tracking by remotely measuring ocean temperature profiles without the need for a precision interferometer.
A further object is the provision of such a method that permits submarine detection long after the vessel has passed the search area.